Fun little test. I got 480.
Their answer to #16 is wrong. Since the ropes are angled somewhat the
actual force would be more than 50kg. (And besides, kg are a unit of
mass, not force. The actual force would be a bit more than 9.8 * 50
I too think their answer in #31 is wrong, and some of their electrical
symbols are a bit funky.
I got wrong the pipe one wrong. I expect that Bernoulli's principle
means that the pressure is lower in the narrower section.
I also got the "naturally aspirated engine" one wrong. I said it was
suction from the piston, but really that wouldn't cause anything to
happen without atmospheric pressure pushing it in, so I guess I can't
Vacuum is the default. The voids of space are a vacuum.
Atmosphere and its pressure are the aberration.
The piston is mechanically pulled down to create a condition akin to a
The mere presence of an atmosphere allows a flow to occur TO the
The atmospheric pressure does NOT create a vacuum. In the piston's
case, a mechanical event creates a vacuum. The void created by
removing atmospheric pressure creates the vacuum, therefore......
Again, this one is debatable as both 'Suction' and 'Atmospheric Pressue' are
As the piston goes down, it results in lowering the air pressure inside the
chamber. Thus there is now a difference in pressure between inside the
chamber and outside. It's this difference in air pressure that results in
air flowing into the chamber.
Of course the piston going down creates a lower pressure in the chamber,
which results in 'sucking' the air in.
Both answers are correct.
No they are not.
Atmospheric pressure is 14.6 PSIA A little over 14 psi over nothing.
Nothing (vacuum) is the default.
The downward pull of the piston is created by a mechanical input.
The atmosphere simply fills that void...it surely does not CREATE the
I think this one's reasonable - it's multi-choice, you do know that it's
one of the answers, and _only_ one of the answers. With that extra
axiom, the answer is clearly "atmospheric pressure" rather than
Given what I learned from the balloons question, I think it's actually
local variations in non-constant air pressure between cylinders...
Cats have nine lives, which is why they rarely post to Usenet.
The fan blowing on the fan is an ambiguous question. They're facing each
other, and spinning the "same" direction, in the sense that when viewed from
the side, they're both spinning down on the edge facing you (or up, depending
on which side you're on). But when each one is viewed from *its*own* front,
one is spinning clockwise, and the other counterclockwise.
So is that the same direction? Or the opposite direction?
Doug Miller (alphageek at milmac dot com)
On Oct 23, 8:04 pm, email@example.com (Doug Miller) wrote:
Both blades rotate in the same direction regardless of vantage point.
You stand behind one fan, and both blades turn clockwise. You stand
behind the other, both blades turn anti-clockwise. What on earth is so
hard about that, oh wise one?
The confusion is "same direction" and where the observer stands when
evaluating the direction of each fan. Part of this test is
understanding the question. I should have got a perfect score with my
background and education, but did not. I excel at engineering and
math, but English comprehension is another story.
You could look at it this way: The fan that is running is turning in its
normal direction, and the fan that is not running is turning opposite of
its normal direction. Therefore, they are turning in opposite
directions. This reasoning makes the most sense to me, because it takes
point of view totally out of the equation.
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